I've had three different types of Cateye rear lights and a Knog Skink and all of these stop working after a wet ride.
I really like the Skink apart from it's non-waterproofness. It's good to be able to swap it between bikes without having to mess about with a screwdriver.
I ride to work and back every day, regardless of the weather, and being in Edinburgh that means it's often in the wet.
Anyone got a rear light that can stand up to this kind of treatment?

I've been using Cateye Au100s for years – and they work fine.

I've been using pretty basic cateyes for years, and never had one die due to weather.

Due to smacking them onto rocks, now that is another matter.

I've got mudguards, which I guess protect the lights from a lot of the scum and wet, if you haven't, maybe that's why your lights are dead? (commuting in this weather with mudguards is great – I just got in, and whilst my top half was a bit damp, my trousers were pretty dry, they dried off in 5 minutes, despite the roads being really wet (and it raining on me for an hour).

Joe

Try a Blackburn Mars 3.0

Nice, tight screw together case. Bright as well and has little orange side LEDs. I like the mount too which is basically a belt clip permanently attached to the light which then clips into the bracket.

I've been using mine commuting in Edinburgh for a few months now with no probs.

have you considered one of the new Knog rear lights (Gekko?)

http://www.sustransshop.co.uk/products/5513-knog-gekko-microlight—rear

Another vote for the Mars

Backupz 5 led rear lights for me. I use two and they're bright and have been faultless despite multiple soakings.

wet mars here, no probs in 18 months

pinches – Member

have you considered one of the new Knog rear lights (Gekko?)

TBH the Gekko's a bit pants in the wet.

Sounds like it could be worth trying out one of these Blackburn Mars lights then. Looks like it could be a bit of a hassle moving it from one bike to another though.

One thing I did think about doing was putting some rubber glue (sole seal) between the rubber and the plastic on the Knog round all the openings. Would need to re-glue every time I changed the batteries though.

the mini-review in last ST mag suggests the skink is waterproof. Yay, I thought and bought one. It really isn't. I did clean up the battery connections, get the mud/grit out of the inside of the microswitch and solder the incredibly tiny-wired dead connection back together 8) but little point in popping it on the back of my xc bike for big wet night rides. 🙁

This similar thread a few weeks ago had someone saying that despite the great sealing everywhere else, the switch on the Mars lets in water. Mine lives under the saddle over a full mudguard on my work bike, so gets little or no spray or rain in that direction.

Bought my son a Knogg Gekko a few weeks ago from wiggle and it has stopped working already – looks corroded inside! 🙁

It seems that the Knog lights are most certainly not water resistant.
I think I'm going to go ahead and try sealing mine with some sealant and see if that works.

How do manufacturers get away with calling things "Water resistant" when all they really mean is that electrical contacts are not completely open to the elements and not that they have any kind of sealing?

Various Cateyes over a long time and never had a problem with water ingress. I think you really must have been unlucky. I think that most Cateye products are hard to beat in my experience. Have you tried a smear of silicone grease around any joints? Might work for you.

I've got mudguards, which I guess protect the lights from a lot of the scum and wet, if you haven't, maybe that's why your lights are dead?

What he said- I've never had a rear light die because of water getting in. If it's just a commuter get some guards and be done with it!

I really like the Skink apart from it's non-waterproofness. It's good to be able to swap it between bikes without having to mess about with a screwdriver.

I've also just got a Skink for the same reasons, just for the odd occasion I need a decent-ish rear light on my MTB or roadie and I think it'll do fine for that. But it's clearly not waterproof/resistant in any meaningful sense- I wouldn't consider it for an everyday commuting light.

My Tesco rear(£1 odd) which is fixed under my seat seems to be survivng pretty well considering the rivers we have been riding in over the past few weeks.